A backdrill alignment detection board and its detection method

Abstract

The present invention relates to the technical field of PCBs, and discloses a backdrill alignment detection board and a detection method thereof. The backdrill alignment detection board includes a circuit board body, which is divided into a non-through drilling layer to be backdrilled and a through drilling layer to be backdrilled; in the non-through drilling layer to be backdrilled, a first test ring is made on the outer periphery of a drilling hole to be made, and the first test ring is circumferentially divided into at least two mutually disconnected first arc segments along the hole circumference; in the through drilling layer to be backdrilled, a second test ring is made on the outer periphery of the backdrilling hole to be made, and the second test ring is circumferentially divided into at least two mutually disconnected second arc segments along the hole circumference. The embodiment of the present invention abandons visual inspection and slicing operations, can completely eliminate the defects of large workload, strong subjectivity and relatively one-sided inspection results existing in the visual inspection method and the slicing inspection method, and can not only detect the absolute offset between the drilling hole and the backdrilling hole, but also analyze and obtain the relative offset between the drilling hole and the backdrilling hole, and the detection result is effective and accurate.

Description

Technical Field

[0001] The present invention relates to the technical field of PCB (Printed Circuit Boards), and particularly relates to a backdrill alignment detection board and a detection method thereof. Background Art

[0002] With the increasing speed and frequency of signal transmission, the integrity of signals has become an increasingly important core of PCB. However, in the traditional design of plated through holes (PTH), there are always some hole coppers that do not play any connection role. This hole copper is called a stub, also known as a stub, which can cause problems such as reflection, scattering, and delay of high-frequency and high-speed signals.

[0003] The process of drilling out the stub is called backdrilling. Backdrilling is a special drilling technology for controlling the drilling depth: based on the first drill, a drill bit with a larger diameter than the first drill is used to drill out the useless copper in the first drill. During the processing, due to the deviation of the coincidence degree between the backdrill and the first drill, there will be a phenomenon of "copper hanging" on the hole wall of the first drill, as specifically shown in Figure 1 As shown. Therefore, at present, the alignment of backdrilling is mainly judged by visual inspection and sectioning methods.

[0004] (1) Visual inspection method: Observe from the backdrill entrance surface to the inside through a ten-fold magnifying glass to check whether the first drill is tangent to the backdrill or the center is offset. However, this method has a large workload; moreover, as the backdrill depth increases, the lens cannot focus on the position of the first drill;

[0005] (2) Sectioning method: Observe through sectioning. However, since the sectioning can only observe the backdrill offset amount of one vertical / horizontal section, the result is relatively one-sided. Summary of the Invention

[0006] The purpose of the present invention is to provide a backdrill alignment detection board and a detection method thereof to solve the problems existing in the prior art, such as large detection workload and relatively one-sided detection results.

[0007] To achieve this purpose, the present invention adopts the following technical solutions:

[0008] A backdrill alignment detection board includes a circuit board body. The circuit board body is divided into at least one layer of a proposed non-backdrilled layer that is not proposed to be drilled through by backdrilling and at least one layer of a proposed backdrilled layer that is proposed to be drilled through by backdrilling along the backdrill drilling direction;

[0009] In the proposed non-backdrilled layer of the circuit board body, a first test ring is made on the outer periphery of the first theoretical production position where a drill hole is proposed to be made, and the first test ring is divided into at least two mutually disconnected first arc segments along the circumferential direction of the proposed drill hole;

[0010] On the virtual back-drilling through layer of the circuit board body, a second test ring is fabricated on the outer periphery of the second theoretical fabrication position where the back-drilling is to be made, and the second test ring is circumferentially divided into at least two mutually disconnected second arc segments along the circumference of the proposed back-drilling;

[0011] Wherein, the first theoretical fabrication position and the second theoretical fabrication position are coaxially arranged.

[0012] Optionally, the first test ring and the second test ring are divided in the same way, so that each of the first arc segments and each of the second arc segments are vertically aligned one by one.

[0013] Optionally, at least two groups of test units are also fabricated on the circuit board body, and each group of test units corresponds to a group of vertically aligned first arc segments and second arc segments.

[0014] Optionally, the test unit includes a first metallized test hole, a second metallized test hole and a third metallized test hole;

[0015] The first metallized test hole is electrically connected to one end of the corresponding first arc segment in the arc length direction, the second metallized test hole is electrically connected to the other end of the corresponding first arc segment in the arc length direction and one end of the corresponding second arc segment in the arc length direction at the same time, and the third metallized test hole is electrically connected to the other end of the corresponding second arc segment in the arc length direction.

[0016] Optionally, the second metallized test hole penetrates through the other end of the corresponding first arc segment in the arc length direction.

[0017] Optionally, the inner diameter of the first test ring is equal to the theoretical drilling aperture of the one-drilling, and the width is equal to the maximum allowable offset under the current one-drilling alignment detection level;

[0018] The inner diameter of the second test ring is equal to the theoretical drilling aperture of the back-drilling, and the width is equal to the maximum allowable offset under the current back-drilling alignment detection level.

[0019] A back-drilling alignment detection method includes:

[0020] On the circuit board body of the back-drilling alignment detection board as described in any one of the above, first make a one-drilling according to the first theoretical fabrication position, and then make a back-drilling according to the second theoretical fabrication position;

[0021] Detect whether each of the first arc segments of the first test ring is drilled through, and accordingly judge the absolute offset information of the one-drilling;

[0022] Detect whether each second arc segment of the second test ring is drilled through, and judge the absolute offset information of the back drill hole accordingly; the absolute offset information includes the offset range and the offset direction;

[0023] According to the absolute offset information of the first drill hole and the absolute offset information of the back drill hole, analyze and obtain the relative offset information between the first drill hole and the back drill hole.

[0024] Optionally, the first test ring and the second test ring are divided in the same way, so that each first arc segment and each second arc segment are vertically aligned in one-to-one correspondence; at least two groups of test units are also manufactured on the circuit board, and each group of test units corresponds to a group of first arc segments and second arc segments that are vertically aligned;

[0025] The test unit includes a first metallized test hole, a second metallized test hole and a third metallized test hole; the first metallized test hole is electrically connected to one end of the corresponding first arc segment in the arc length direction, and the second metallized test hole is electrically connected to the other end of the corresponding first arc segment in the arc length direction and one end of the corresponding second arc segment in the arc length direction at the same time, and the third metallized test hole is electrically connected to the other end of the corresponding second arc segment in the arc length direction.

[0026] According to the electrical conduction state between the first metallized test hole and the second metallized test hole in each test unit, judge whether each first arc segment of the first test ring is drilled through;

[0027] According to the electrical conduction state between the second metallized test hole and the third metallized test hole in each test unit, judge whether each second arc segment of the second test ring is drilled through.

[0028] Compared with the prior art, the beneficial effects of the present invention are:

[0029] In the embodiment of the present invention, a test ring is respectively manufactured on the non-through drilling layer and the through drilling layer to be back drilled of the circuit board body, and the test ring is segmented; subsequently, a first drill hole and a back drill hole can be made in the test ring, and the actual offset conditions of the first drill hole and the back drill hole can be judged by detecting whether each part segment of the test ring is drilled through. This method abandons visual inspection and slicing operations, and can completely eliminate the defects of large workload, strong subjectivity and relatively one-sided inspection results existing in the visual inspection method and the slicing inspection method. Moreover, it can not only detect the absolute offset conditions of the first drill hole and the back drill hole, but also analyze and obtain the relative offset conditions between the first drill hole and the back drill hole, and the detection results are effective and accurate. Description of the Drawings

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0031] Figure 1 (1) and (2) are schematic comparison diagrams of a conventional first drill and back drill in the case of alignment and non - alignment.

[0032] Figure 2 It is a transverse cross - sectional view of the back - drill alignment detection board provided by the embodiment of the present invention.

[0033] Figure 3 It is a three - dimensional structure diagram of the back - drill alignment detection board provided by the embodiment of the present invention.

[0034] Figure 4 It is a flow chart of the back - drill alignment detection method provided by the embodiment of the present invention.

[0035] Explanation of reference numerals: The first test ring 1, the second test ring 2, the first drill hole 3, the back - drill hole 4, the first metallized test hole 5, the second metallized test hole 6, the third metallized test hole 7. Detailed implementation manners

[0036] To make the invention purpose, features, and advantages of the present invention more obvious and understandable, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0037] Back - drilling is a special drilling technique for controlling the drilling depth: based on a first drill hole, a drill bit with a diameter ≥ that of the first drill is used to drill off the useless copper inside the first drill hole to form a back - drill hole. It can be seen that the first drill hole is a through - hole structure penetrating the upper and lower plate surfaces of the circuit board body, and the back - drill hole is obtained by reaming the upper - segment hole section of the first drill hole with one side plate surface of the circuit board body as the drilling surface, that is, the depth of the back - drill hole is less than that of the first drill hole, so that part of the core board of the circuit board body is penetrated by the back - drill and part is not. Therefore, for the convenience of description, the circuit board body will be divided into a proposed non - penetrated layer by back - drill and a proposed penetrated layer by back - drill according to the back - drill direction.

[0038] To achieve simple and effective alignment detection of a one-drill and a back-drill, an embodiment of the present invention provides a back-drill alignment detection board, which respectively manufactures a test ring on the non-through-drilling layer and the through-drilling layer to be back-drilled of the circuit board body, and segments the test ring; subsequently, a drilling hole 3 and a back-drilling hole 4 can be made in the test ring, and by detecting whether each segmented part of the test ring is drilled off, the actual offset situation of the drilling hole 3 and the back-drilling hole 4 can be judged. This method abandons visual inspection and slicing operations, can completely eliminate the defects of large workload, strong subjectivity and relatively one-sided inspection results existing in the visual inspection method and the slicing inspection method, and can not only detect the absolute offset situation between the drilling hole 3 and the back-drilling hole 4, but also analyze and obtain the relative offset situation between the drilling hole 3 and the back-drilling hole 4, and the detection result is effective and accurate.

[0039] Please refer to Figure 2 and Figure 3 , the back-drill alignment detection board provided by the embodiment of the present invention includes a circuit board body.

[0040] On the non-through-drilling layer to be back-drilled of the circuit board body, a first test ring 1 is manufactured on the outer periphery of the first theoretical manufacturing position where the drilling hole 3 is to be made, and the first test ring 1 is circumferentially divided into at least two mutually disconnected first arc segments along the circumference of the drilling hole 3 to be made. Among them, the first theoretical manufacturing position refers to the theoretical drilling position of the drilling hole 3 on the circuit board body.

[0041] On the through-drilling layer to be back-drilled of the circuit board body, a second test ring 2 is manufactured on the outer periphery of the second theoretical manufacturing position where the back-drilling hole 4 is to be made, and the second test ring 2 is circumferentially divided into at least two mutually disconnected second arc segments along the circumference of the back-drilling hole 4 to be made. Among them, the second theoretical manufacturing position refers to the theoretical drilling position of the back-drilling hole 4 on the circuit board body, and is coaxially arranged with the first theoretical manufacturing position.

[0042] It should be noted that in the actual processing process, if the actual manufacturing position of the drilling hole 3 deviates from the theoretical manufacturing position, the obtained drilling hole 3 is bound to intersect with the first test ring 1 on its outer periphery. When the offset amount reaches a certain degree, the drilling hole 3 will completely drill off the first test ring 1. Therefore, according to the state of the first test ring 1, it can be judged whether the drilling hole 3 actually has an absolute offset and the actual offset degree.

[0043] Similarly, if the actual manufacturing position of the back-drill deviates from the theoretical manufacturing position, the obtained back-drilling hole 4 is bound to intersect with the second test ring 2 on its outer periphery. When the offset amount reaches a certain degree, the back-drilling hole 4 will completely drill off the second test ring 2. Therefore, according to the state of the second test ring 2, it can be judged whether the back-drilling hole 4 actually has an absolute offset and the actual offset degree.

[0044] Further, since the first test ring 1 and the second test ring 2 are segmented along the hole circumference in the embodiments of the present invention, and each arc segment is separately detected, the approximate position where each test ring is drilled through can be identified, so as to determine the absolute offset direction of a drilling hole 3 and the absolute offset direction of a back drilling hole 4.

[0045] Therefore, based on the segmented detection results of the first test ring 1 and the second test ring 2, the absolute offset conditions (including the offset direction and the offset degree) of the drilling hole 3 and the back drilling hole 4 can be respectively determined; on this basis, according to the absolute offset conditions of the drilling hole 3 and the back drilling hole 4, the relative offset condition between the drilling hole 3 and the back drilling hole 4 can be further analyzed.

[0046] In practical applications, the first test ring 1 and the second test ring 2 can adopt different division methods (such as: the number of segments, the segment positions), and in order to improve the production and detection efficiency, the same division method (including the number of segments and the segment positions) can also be adopted, so that the upper and lower positions of each first arc segment and each second arc segment correspond one by one.

[0047] Further, as Figure 3 shown, in order to implement the detection function of each arc segment, at least two groups of test units are also made on the circuit board body, and each group of test units corresponds to a group of first arc segments and second arc segments with corresponding upper and lower positions.

[0048] The test unit includes a first metallized test hole 5, a second metallized test hole 6 and a third metallized test hole 7; the first metallized test hole 5 is electrically connected to one end of the corresponding first arc segment in the arc length direction, the second metallized test hole 6 is electrically connected to the other end of the corresponding first arc segment in the arc length direction and one end of the corresponding second arc segment in the arc length direction at the same time, and the third metallized test hole 7 is electrically connected to the other end of the corresponding second arc segment in the arc length direction.

[0049] Exemplarily, the second metallized test hole 6 penetrates through the other end of the corresponding first arc segment in the arc length direction and is electrically connected to one end of the corresponding second arc segment in the arc length direction through the inner layer pattern.

[0050] At this time, compared with the method of using four vias to separately detect two arc segments, applying three metallized test vias to simultaneously detect the states of the upper and lower two arc segments realizes the reuse of one metallized test hole, can effectively save space and improve the wiring density.

[0051] In an embodiment of the present invention, the inner diameter of the first test ring 1 is equal to the theoretical drilling aperture of a drilling hole 3, and the width is equal to the maximum allowable offset under the current detection level of the alignment degree of the first drilling; the inner diameter of the second test ring 2 is equal to the theoretical drilling aperture of the back drilling hole 4, and the width is equal to the maximum allowable offset under the current detection level of the alignment degree of the back drilling. Based on this, when a certain first arc segment of the first test ring 1 is completely drilled through, it indicates that the actual offset of the drilling hole 3 has reached the maximum allowable offset under the current detection level of the alignment degree of the first drilling; similarly, when a certain second arc segment of the second test ring 2 is completely drilled through, it indicates that the offset of the back drilling hole 4 has reached the maximum allowable offset under the current detection level of the alignment degree of the back drilling. Therefore, the width of the test ring can be designed according to the actual alignment degree requirement.

[0052] In practical applications, in order to determine the maximum alignment ability of a drilling hole 3 (or a back drilling hole 4), multiple groups of first test rings 1 (or second test rings 2) can be manufactured simultaneously, and the widths of the respective first test rings 1 (or second test rings 2) are set according to a preset gradient. After manufacturing a drilling hole 3 (or a back drilling hole 4) in each first test ring 1 respectively and then performing detection, among the groups of first test rings 1 (or second test rings 2) that are completely drilled through, the width value of the first test ring 1 (or second test ring 2) with the smallest width can represent the maximum alignment ability of the drilling hole 3 (or the back drilling hole 4).

[0053] Please refer to Figure 4 , an embodiment of the present invention provides a method for detecting the alignment degree of back drilling, including:

[0054] Step 101: On the circuit board body of the back drilling alignment degree detection board as described above, first manufacture a drilling hole 3 according to the first theoretical manufacturing position, and then manufacture a back drilling hole 4 according to the second theoretical manufacturing position.

[0055] Step 102: Detect whether each first arc segment of the first test ring 1 is drilled through, and accordingly judge the absolute offset information of the drilling hole 3; detect whether each second arc segment of the second test ring 2 is drilled through, and accordingly judge the absolute offset information of the back drilling hole 4.

[0056] Step 103: Analyze and obtain the relative offset information between the drilling hole 3 and the back drilling hole 4 according to the absolute offset information of the drilling hole 3 and the absolute offset information of the back drilling hole 4.

[0057] Taking Figure 3 as an example, if it is detected that the first arc segment in the upper left corner of the first test ring 1 is drilled through and the first arc segments in other directions are not drilled through, it can be determined that the drilling hole 3 deflects to the upper left corner, and the offset amount reaches the width value of the first test ring 1.

[0058] If it is detected that the second arc segment in the lower right of the second test ring 2 is drilled through and the second arc segments in other directions are not drilled through, it can be determined that the back drill hole 4 is offset to the lower right, and the offset amount reaches the width value of the second test ring 2.

[0059] Furthermore, on the basis that a drill hole 3 is offset to the upper left and the offset amount reaches the width value of the first test ring 1, and the back drill hole 4 is offset to the lower right and the offset amount reaches the width value of the second test ring 2, it can be analyzed that the relative offset direction of the back drill hole 4 relative to the drill hole 3 is to the lower right, and the offset amount reaches the sum of the width value of the first test ring 1 and the width value of the second test ring 2.

[0060] Therefore, based on the method of the embodiment of the present invention, the absolute offset information of the drill hole 3, the absolute offset information of the back drill hole 4, and the relative offset information between the drill hole 3 and the back drill hole 4 can be quickly and accurately detected.

[0061] As mentioned above, the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A back drilling alignment detection board, characterized in that, It includes a circuit board body, and the circuit board body is divided along the backdrilling direction into at least one non-backdrilled layer that is not intended to be drilled through by backdrilling and at least one backdrilled layer that is intended to be drilled through by backdrilling; In the non-backdrilled layer of the circuit board body, a first test ring is made on the outer periphery of the first theoretical production position where a drill hole is intended to be made, and the first test ring is divided along the circumferential direction of the drill hole to be made into at least two mutually disconnected first arc segments; In the backdrilled layer of the circuit board body, a second test ring is made on the outer periphery of the second theoretical production position where a backdrill hole is intended to be made, and the second test ring is divided along the circumferential direction of the backdrill hole to be made into at least two mutually disconnected second arc segments; Wherein, the first theoretical production position and the second theoretical production position are coaxially arranged; The first test ring and the second test ring are divided in the same way, so that each of the first arc segments and each of the second arc segments correspond one by one in the up and down positions.

2. The back drilling alignment detection board according to claim 1, wherein At least two groups of test units are also made on the circuit board body, and each group of test units corresponds to a group of first arc segments and second arc segments that are in corresponding up and down positions.

3. The back drilling alignment detection board according to claim 2, characterized in that The test unit includes a first metallized test hole, a second metallized test hole and a third metallized test hole; The first metallized test hole is electrically connected to one end of the corresponding first arc segment in the arc length direction, the second metallized test hole is electrically connected to the other end of the corresponding first arc segment in the arc length direction and one end of the corresponding second arc segment in the arc length direction at the same time, and the third metallized test hole is electrically connected to the other end of the corresponding second arc segment in the arc length direction.

4. The back drill alignment detection board according to claim 3, characterized in that, The second metallized test hole penetrates through the other end of the corresponding first arc segment in the arc length direction.

5. The back drilling alignment detection board according to claim 1, characterized in that, The inner diameter of the first test ring is equal to the theoretical drill hole diameter of the drill hole, and the width is equal to the maximum allowable offset under the current first drill alignment detection level; The inner diameter of the second test ring is equal to the theoretical drill hole diameter of the backdrill hole, and the width is equal to the maximum allowable offset under the current backdrill alignment detection level.

6. A back drilling alignment detection method, characterized in that, It includes: On the circuit board body of the backdrill alignment detection board according to any one of claims 1 to 5, first make a drill hole according to the first theoretical production position, and then make a backdrill hole according to the second theoretical production position; Detect whether each of the first arc segments of the first test ring is drilled off, and accordingly judge the absolute offset information of the drill hole; Detect whether each of the second arc segments of the second test ring is drilled off, and accordingly judge the absolute offset information of the backdrill hole; the absolute offset information includes the offset range and the offset direction; According to the absolute offset information of the drill hole and the absolute offset information of the backdrill hole, analyze and obtain the relative offset information between the drill hole and the backdrill hole.

7. The backdrill alignment detection method according to claim 6, wherein The first test ring and the second test ring are divided in the same way, so that each of the first arc segments and each of the second arc segments correspond one by one in the up and down positions; at least two groups of test units are also made on the circuit board body, and each group of test units corresponds to a group of first arc segments and second arc segments that are in corresponding up and down positions; The test unit includes a first metallized test hole, a second metallized test hole, and a third metallized test hole; The first metallized test hole is electrically connected to one end of the corresponding first arc segment in the arc length direction, the second metallized test hole is electrically connected to the other end of the corresponding first arc segment in the arc length direction and one end of the corresponding second arc segment in the arc length direction at the same time, and the third metallized test hole is electrically connected to the other end of the corresponding second arc segment in the arc length direction; According to the electrical conduction state between the first metallized test hole and the second metallized test hole in each of the test units, it is determined whether each first arc segment of the first test ring is drilled through; According to the electrical conduction state between the second metallized test hole and the third metallized test hole in each of the test units, it is determined whether each second arc segment of the second test ring is drilled through.

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